What is the Marketplace?
In the Marketplace you can browse through all of the issues that have been flagged as available for sale/trade by other users.

If you find something you are interested in, you will be given the opportunity to send a message to the user so that the two of you might be able to work a deal out.

Can I compare the issues in my wishlist to what is available in the Marketplace?
Yes. Go to your profile page. In your wishlist section should be a link that says, "Check your wishlist in the Marketplace". This link is only available to you if you're logged in. It is also available from your main Wishlist page.